King loves right flipping castle (4)
I believe the answer is:
rook
'castle' is the definition.
(I know that castle can be written as rook)
'king loves right flipping' is the wordplay.
'king' becomes 'K' (abbreviation for king in chess).
'loves' becomes 'oo' (two O's - 'love' means zero in tennis).
'right' becomes 'r' (common abbreviation).
'flipping' is a reversal indicator.
'k'+'oo'+'r'='koor'
'koor' written backwards gives 'ROOK'.
(Other definitions for rook that I've seen before include "Use deceit to get money" , "Gregarious black bird" , "Another name for castle in chess" , "man for moving" , "Man in game" .)